330 ELM ST VIEW RIDGE ESTATES 2022-04-04

M Geotechnical Engineering Evaluation NGA File No. 1085419 View Ridge Estates 330 Building Settlement March 22,2019 Everett,Washington Page 6 are further discussed in the Foundation Underpinning Improvements and Slab-on-Grade Repairs subsection of this report. We should review underpinning plans prior to implementation. It is likely that portions of the structure not currently showing signs of distress may also underlain by the loose fill material encountered in our explorations. Under this scenario, underpinning only the currently distressed portions of the structure and slabs may create a situation where the remaining portions of the structure may start to settle after the distressed portions are underpinned. We recommend that after the recommended underpinning is completed, the structure be monitored for any signs of further distress, and additional pin piles or anchors installed if signs of further distress are observed. In addition to the foundation improvements, we recommend that the drainage system surrounding the building be investigated and improved, as necessary. Such improvements should include confirming the placement of footing drains around the building and routing all downspouts and runoff from all hard surfaces into a permanent discharge system. This is further discussed in the Drainage Improvements subsection of this report. Erosion Control Measures The erosion hazard for the on-site soils is interpreted to be slight, but actual erosion potential will be dependent on how the site is graded and how water is allowed to concentrate. Best Management Practices (BMPs) should be used to control erosion. Areas disturbed during construction should be protected from erosion. Erosion control measures may include diverting surface water away from the stripped areas and erecting silt fences to prevent muddy water from leaving the site. We also recommend that any soil stockpiles and excavation walls be covered with plastic sheeting and not placed near the steep slope. The erosion potential of areas not disturbed should be low. Temporary Slopes Some excavations may be needed to reach final pier locations. Temporary cut slope stability is a function of many factors, including the type and consistency of soils, depth of the cut, surcharge loads adjacent to the excavation, length of time a cut remains open, and the presence of surface water or groundwater. It is exceedingly difficult under these variable conditions to estimate a stable, temporary, cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe slope configurations since they are continuously at the job site, able to observe the soil and groundwater conditions encountered, and able to monitor the nature and condition of the cut slopes. The following information is provided solely for the benefit of the owner and other design consultants and should not be construed to imply that Nelson Geotechnical Associates, Inc. assumes responsibility for job site safety. Job site safety is the sole responsibility of the project contractor. (71 0:1 NELSON GEOTECHNICAL ASSOCIATES, INC.